Emergence and evolution of internationally disseminated cephalosporin-resistant Neisseria gonorrhoeae clones from 1995 to 2005 in Japan

Molecular epidemiological and antimicrobial-resistant mechanisms analysis of prolonged Neisseria gonorrhoeae collection between 1971 and 2005 in Japan

Objectives

As antimicrobial-resistant (AMR) Neisseria gonorrhoeae strains have emerged, humans have adjusted the antimicrobials used to treat infections. We identified shifts in the N. gonorrhoeae population and the determinants of AMR strains isolated during the recurring emergence of resistant strains and changes in antimicrobial therapies.

Methods

We examined 243 N. gonorrhoeae strains corrected at the Kanagawa Prefectural Institute of Public Health, Kanagawa, Japan, these isolated in 1971-2005. We performed multilocus sequence typing and AMR determinants (penA, mtrR, porB, ponA, 23S rRNA, gyrA and parC) mainly using high-throughput genotyping methods together with draft whole-genome sequencing on the MiSeq (Illumina) platform.

Results

All 243 strains were divided into 83 STs. ST1901 (n = 17) was predominant and first identified after 2001. Forty-two STs were isolated in the 1970s, 34 in the 1980s, 22 in the 1990s and 13 in the 2000s, indicating a decline in ST diversity over these decades. Among the 29 strains isolated after 2001, 28 were highly resistant to ciprofloxacin (MIC ≥ 8 mg/L) with two or more amino-acid substitutions in quinolone-resistance-determining regions. Seven strains belonging to ST7363 (n = 3), ST1596 (n = 3) and ST1901 (n = 1) were not susceptible to cefixime, and six strains carried penA alleles with mosaic-like penicillin-binding protein 2 (PBP2; penA 10.001 and 10.016) or PBP2 substitutions A501V and A517G.

Conclusions

We observed a significant reduction in the diversity of N. gonorrhoeae over 35 years in Japan. Since 2001, ST1901, which is resistant to ciprofloxacin, has superseded previous strains, becoming the predominant ST population.

penA profile of Neisseria gonorrhoeae in Guangdong, China: Novel penA alleles are related to decreased susceptibility to ceftriaxone or cefixime

BACKGROUND

Resistance to extended-spectrum cephalosporins (ESCs) has become a public health concern with the spread of Neisseria gonorrhoeae and increasing antimicrobial resistance. Mutation of penA, encoding penicillin-binding protein 2, represents a mechanism of ESC resistance. This study sought to assess penA alleles and mutations associated with decreased susceptibility (DS) to ESCs in N. gonorrhoeae.

MATERIALS AND METHODS

In 2021, 347 gonococci were collected in Guangdong, China. Minimum inhibitory concentations (MICs) of ceftriaxone and cefixime were determined, and whole-genome sequencing and phylogenetic analysis were performed. Multi-locus sequence typing (MLST) and conventional resistance determinants such as penA, mtrR, PonA and PorB were analysed. penA was genotyped and sequence-aligned using PubMLST.

RESULTS

Genome-wide phylogenetic analysis revealed that the prevalence of DS to ESCs was highest in Clade 11.1 (100.0%), Clade 2 (66.7%) and Clade 0 (55.7%), and the leading cause was strains with penA-60.001 or new penA alleles in clades. The penA phylogenetic tree is divided into two branches: non-mosaic penA and mosaic penA. The latter contained penA-60.001, penA-10 and penA-34. penA profile analysis indicated that A311V and T483S are closely related to DS to ESCs in mosaic penA. The new alleles NEIS1753_2840 and NEIS1753_2837 are closely related to penA-60.001, with DS to ceftriaxone and cefixime of 100%. NEIS1753_2660, a derivative of penA-10 (A486V), has increased DS to ceftriaxone. NEIS1753_2846, a derivative of penA-34.007 (G546S), has increased DS to cefixime.

CONCLUSION

This study identified critical penA alleles related to elevated MICs, and trends of gonococcus-evolved mutated penA associated with DS to ESCs in Guangdong.

Bacitracin enhances ceftriaxone susceptibility of the high-level ceftriaxone-resistant gonococcal FC428 clone

IMPORTANCE

Ceftriaxone-based antimicrobial therapies for gonorrhea are threatened by waning ceftriaxone susceptibility levels and the global dissemination of the high-level ceftriaxone-resistant gonococcal FC428 clone. Combination therapy can be an effective strategy to restrain the development of ceftriaxone resistance, and for that purpose, it is important to find an alternative antimicrobial to replace azithromycin, which has recently been removed in some countries from the recommended ceftriaxone plus azithromycin dual-antimicrobial therapy. Ideally, the second antimicrobial should display synergistic activity with ceftriaxone. We hypothesized that bacitracin might display synergistic activity with ceftriaxone because of their distinct mechanisms targeting bacterial cell wall synthesis. In this study, we showed that bacitracin indeed displays synergistic activity with ceftriaxone against Neisseria gonorrhoeae. Importantly, strains associated with the FC428 clone appeared to be particularly susceptible to the bacitracin plus ceftriaxone combination, which might therefore be an interesting dual therapy for further in vivo testing.

Antimicrobial susceptibilities and genomic epidemiology of Neisseria gonorrhoeae in Stockholm, Sweden

The aim of this study was to investigate the genomic epidemiology and antimicrobial susceptibilities of N. gonorrhoeae isolates in Stockholm, Sweden. In total, 6723 isolates detected in Stockholm, Sweden, from January 2016 to September 2022, were examined for antimicrobial susceptibilities by using E-test. Whole-genome sequencing (WGS) was applied to isolates in sentinel surveillance and isolates resistant to extended-spectrum cephalosporins (ESCs) or high-level azithromycin (HLAzi-R, MIC ≥ 256 mg/L). As sentinel surveillance, consecutive clinical isolates (n = 396) detected every 4th week from January 2021 to September 2022 were enrolled in the study. Of the 6723 isolates investigated, 33 isolates (< 1%) were found to be resistant to cefixime, one of which was co-resistant to ceftriaxone and ciprofloxacin and was detected in September 2022. Ten isolates presented a high level of azithromycin resistance. Resistant rates to ciprofloxacin varied from 32 in 2017 to 68-69% in 2021-2022. Elevated MIC50 and MIC90 of azithromycin were observed over the years. No resistance to spectinomycin was identified. The most frequently occurring MLST in the sentinel surveillance was ST9362 (23%), followed by ST11706 (9%), ST7359 (8%), ST10314 (7%), and ST11422 (6%). The ceftriaxone-resistant isolate belonged to ST8130 and the novel NG-STAR ST4859. Genomic resistance traits found in this strain included mutations in genes mtrR (A39T), parC (S87N), and gyrA (S91F and D95A), as well as the presence of blaTEM-135 and tetM genes. A predominance of ST9362 was observed in Stockholm. The high number of azithromycin and ciprofloxacin-resistant isolates and the emergence of a strain with a novel NG-STAR are of great concern.

Whole genome analysis and antimicrobial resistance of Neisseria gonorrhoeae isolates from Ghana

Introduction

Gonorrhoea is a major public health concern. With the global emergence and spread of resistance to last-line antibiotic treatment options, gonorrhoea threatens to be untreatable in the future. Therefore, this study performed whole genome characterization of Neisseria gonorrhoeae collected in Ghana to identify lineages of circulating strains as well as their phenotypic and genotypic antimicrobial resistance (AMR) profiles.

Methods

Whole genome sequencing (WGS) was performed on 56 isolates using both the Oxford Nanopore MinION and Illumina MiSeq sequencing platforms. The Comprehensive Antimicrobial Resistance Database (CARD) and PUBMLST.org/neisseria databases were used to catalogue chromosomal and plasmid genes implicated in AMR. The core genome multi-locus sequence typing (cgMLST) approach was used for comparative genomics analysis.

Results and Discussion

In vitro resistance measured by the E-test method revealed 100%, 91.0% and 85.7% resistance to tetracycline, penicillin and ciprofloxacin, respectively. A total of 22 sequence types (STs) were identified by multilocus sequence typing (MLST), with ST-14422 (n = 10), ST-1927 (n = 8) and ST-11210 (n = 7) being the most prevalent. Six novel STs were also identified (ST-15634, 15636-15639 and 15641). All isolates harboured chromosomal AMR determinants that confer resistance to beta-lactam antimicrobials and tetracycline. A single cefixime-resistant strain, that belongs to N. gonorrhoeae multiantigen sequence type (NG-MAST) ST1407, a type associated with widespread cephalosporin resistance was identified. Neisseria gonorrhoeae Sequence Typing for Antimicrobial Resistance (NG-STAR), identified 29 unique sequence types, with ST-464 (n = 8) and the novel ST-3366 (n = 8) being the most prevalent. Notably, 20 of the 29 STs were novel, indicative of the unique nature of molecular AMR determinants in the Ghanaian strains. Plasmids were highly prevalent: pTetM and pblaTEM were found in 96% and 92% of isolates, respectively. The TEM-135 allele, which is an amino acid change away from producing a stable extended-spectrum β-lactamase that could result in complete cephalosporin resistance, was identified in 28.5% of the isolates. Using WGS, we characterized N. gonorrhoeae strains from Ghana, giving a snapshot of the current state of gonococcal AMR in the country and highlighting the need for constant genomic surveillance.

Dissemination of Neisseria gonorrhoeae with decreased susceptibility to extended-spectrum cephalosporins in Southern China, 2021: a genome-wide surveillance from 20 cities

BACKGROUND

Antimicrobial resistance (AMR) of untreatable gonococcal infection is an emerging threat, especially in Guangdong, a prosperous province in Southern China.

METHODS

N.gonorrhoeae was isolated from 20 cities in Guangdong and determined antimicrobial susceptibility. Through whole-genome sequencing (WGS), multilocus sequence typing (MLST), N.gonorrhoeae multiantigen sequence typing (NG-MAST), and N.gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR) were obtained based on the PubMLST database ( https://pubmlst.org/ ). Phylogenetic analysis was used for dissemination and tracking analysis.

RESULTS

Antimicrobial susceptibility was performed on 347 isolates, and 50 isolates were identified as decreased susceptibility (DS) to cephalosporins. Of which 16.0% (8/50) were ceftriaxone DS, 38.0% (19/50) were cefixime DS, and 46.0% (23/50) were both ceftriaxone and cefixime DS. In all, the dual-resistant rate of the cephalosporin-DS isolates was 96.0% for penicillin and 98.0% for tetracycline-resistant, and 10.0% (5/50) were resistant to azithromycin. All cephalosporin-DS isolates were resistant to ciprofloxacin but sensitive to spectinomycin. The predominant MLSTs were ST7363 (16%, 8/50), ST1903 (14%, 7/50), ST1901 (12%, 6/50), and ST7365 (10%, 5/50). Besides some isolates that failed genotyping (NA), NG-STAR ST1143 (n = 6) and NG-MAST ST17748 (n = 4) were the most prevalent. Twelve isolates with mosaic penA-60.001 allele retained the most elevated cephalosporin MIC (Minimum Inhibitory Concentration). Phylogenetic analysis revealed that epidemic penA-60.001 clones, either domestic or foreign, had spread to nine cities in Guangdong, and 9/12 clones were from the Pearl River Delta region.

CONCLUSIONS

N. gonorrhoeae with cephalosporins-DS was extensively disseminated in Guangdong, Southern China, requiring strict surveillance.

Projecting the development of antimicrobial resistance in Neisseria gonorrhoeae from antimicrobial surveillance data: a mathematical modelling study

BACKGROUND

The World Health Organization recommends changing the first-line antimicrobial treatment for gonorrhoea when ≥ 5% of Neisseria gonorrhoeae cases fail treatment or are resistant. Susceptibility to ceftriaxone, the last remaining treatment option has been decreasing in many countries. We used antimicrobial resistance surveillance data and developed mathematical models to project the time to reach the 5% threshold for resistance to first-line antimicrobials used for N. gonorrhoeae.

METHODS

We used data from the Gonococcal Resistance to Antimicrobials Surveillance Programme (GRASP) in England and Wales from 2000-2018 about minimum inhibitory concentrations (MIC) for ciprofloxacin, azithromycin, cefixime and ceftriaxone and antimicrobial treatment in two groups, heterosexual men and women (HMW) and men who have sex with men (MSM). We developed two susceptible-infected-susceptible models to fit these data and produce projections of the proportion of resistance until 2030. The single-step model represents the situation in which a single mutation results in antimicrobial resistance. In the multi-step model, the sequential accumulation of resistance mutations is reflected by changes in the MIC distribution.

RESULTS

The single-step model described resistance to ciprofloxacin well. Both single-step and multi-step models could describe azithromycin and cefixime resistance, with projected resistance levels higher with the multi-step than the single step model. For ceftriaxone, with very few observed cases of full resistance, the multi-step model was needed to describe long-term dynamics of resistance. Extrapolating from the observed upward drift in MIC values, the multi-step model projected ≥ 5% resistance to ceftriaxone could be reached by 2030, based on treatment pressure alone. Ceftriaxone resistance was projected to rise to 13.2% (95% credible interval [CrI]: 0.7-44.8%) among HMW and 19.6% (95%CrI: 2.6-54.4%) among MSM by 2030.

CONCLUSIONS

New first-line antimicrobials for gonorrhoea treatment are needed. In the meantime, public health authorities should strengthen surveillance for AMR in N. gonorrhoeae and implement strategies for continued antimicrobial stewardship. Our models show the utility of long-term representative surveillance of gonococcal antimicrobial susceptibility data and can be adapted for use in, and for comparison with, other countries.

Whole-Genome Sequencing to Predict Antimicrobial Susceptibility Profiles in Neisseria gonorrhoeae

BACKGROUND

Neisseria gonorrhoeae is a major public health problem due to increasing incidence and antimicrobial resistance. Genetic markers of reduced susceptibility have been identified; the extent to which those are representative of global antimicrobial resistance is unknown. We evaluated the performance of whole-genome sequencing (WGS) used to predict susceptibility to ciprofloxacin and other antimicrobials using a global collection of N. gonorrhoeae isolates.

METHODS

Susceptibility testing of common antimicrobials and the recently developed zolifodacin was performed using agar dilution to determine minimum inhibitory concentrations (MICs). We identified resistance alleles at loci known to contribute to antimicrobial resistance in N. gonorrhoeae from WGS data. We tested the ability of each locus to predict antimicrobial susceptibility.

RESULTS

A total of 481 N. gonorrhoeae isolates, collected between 2004 and 2019 and making up 457 unique genomes, were sourced from 5 countries. All isolates with demonstrated susceptibility to ciprofloxacin (MIC ≤0.06 μg/mL) had a wild-type gyrA codon 91. Multilocus approaches were needed to predict susceptibility to other antimicrobials. All isolates were susceptible to zoliflodacin, defined by an MIC ≤0.25 μg/mL.

CONCLUSIONS

Single marker prediction can be used to inform ciprofloxacin treatment of N. gonorrhoeae infection. A combination of molecular markers may be needed to determine susceptibility for other antimicrobials.

Loop-Mediated Isothermal Amplification Assay for Identifying Neisseria gonorrhoeae Nonmosaic penA-Targeting Strains Potentially Eradicable by Cefixime

Treatment regimens for gonorrhea have limited efficacy worldwide due to the rapid spread of antimicrobial resistance. Cefixime (CFM) is currently not recommended as a first-line treatment for gonorrhea due to the increasing number of resistant strains worldwide. Nonetheless, Neisseria gonorrhoeae strains can be eradicated by CFM at a 400 mg/day dose, provided that the strains are CFM responsive (MIC ≤ 0.064 mg/L). To develop a nonculture test for predicting the CFM responsiveness of N. gonorrhoeae strains, we developed an assay to detect N. gonorrhoeae nonmosaic penA using loop-mediated isothermal amplification (LAMP). To avoid false-positive reactions with commensal Neisseria spp. penA, we amplified specific regions of the N. gonorrhoeae penA (NG-penA-LAMP1) and also the nonmosaic N. gonorrhoeae penA (NG-penA-LAMP3). This assay was validated using isolated N. gonorrhoeae (n = 204) and Neisseria spp. (n = 95) strains. Clinical specimens (n = 95) with confirmed positivity in both culture and real-time PCR were evaluated to validate the system. The combination of the previously described NG-penA-LAMP1 and our new NG-penA-LAMP3 assays had high sensitivity (100%) and specificity (100%) for identifying N. gonorrhoeae carrying the nonmosaic type. To determine whether CFM could be applicable for gonorrhea treatment without culture testing, we developed a LAMP assay that targets penA allele-specific nonmosaic types for use as one of the tools for point-of-care testing of antimicrobial resistance. IMPORTANCE Neisseria gonorrhoeae is among the hot topics of "resistance guided therapy," one of the top 5 urgent antimicrobial threats according to the Centers for Disease Control and Prevention (CDC). There is a need either to develop new agents or to make effective use of existing agents, with the current limited number of therapeutic agents available. Knowing the drug susceptibility information of the target microorganism prior to treating patients is very useful in selecting an effective antibiotic, especially in gonococcal infections where drug resistance is prominent, and is also important in preventing treatment failure. In this study, we developed a new method for obtaining drug susceptibility profiles of Neisseria gonorrhoeae using the loop-mediated isothermal amplification (LAMP) method. The LAMP assay does not require expensive devices. Therefore, this method is expected to be a tool for point-of-care testing of antimicrobial resistance for individualized treatment in the future.

Antimicrobial resistance of <i>Neisseria gonorrhoeae</i> and gonococcal infection therapy: yesterday, today, tomorrow

Implementation of the Russian version of Gonococcal Antimicrobial Surveillance Programme (RU-GASP) in XXI century is summarized. The chronology of evidence-based updating of national clinical guidelines for the gonococcal infection management is outlined. The reasons for penicillins, tetracyclines, and fluoroquinolones excluding from gonococcal infection treatment regimens is presented, and the dynamics of subsequent changes in the sensitivity of N. gonorrhoeae to these antimicrobials is described. The modern schemes of monotherapy of gonococcal infection with third generation cephalosporins and the chronology of increasing their recommended doses are presented. The spectinomycin indications and restrictions for alternative treatment of the gonococcal infection are characterized. The absence of azithromycin in Russian gonococcal infection guideline versus international experience of this antibiotic usage is discussed. Based on current data on the ongoing spread of antimicrobial resistance genetic determinants in N. gonorrhoeae, proposals have been made to improve the RU-GASP protocols and to select drugs for the modern gonococcal infection etiotropic therapy.

Moenomycin is broadly active against multidrug-resistant Neisseria gonorrhoeae and clears an infection from a murine vaginal tract infection model

OBJECTIVES

Ceftriaxone therapy for gonorrhoea has become under increasing pressure due to waning susceptibility levels and emergence of high-level resistant strains such as the FC428 clone. Moenomycin was recently identified to display potent anti-gonococcal activity against some reference strains. Therefore, the aim of this study was to investigate moenomycin in vitro and in vivo antimicrobial activity.

METHODS

Moenomycin in vitro antimicrobial activity was investigated against 575 clinical isolates, including strains associated with the FC428 clone, using the agar dilution method. Moenomycin in vivo activity was investigated in a mouse vaginal tract gonococcal infection model.

RESULTS

The moenomycin MIC range for the strain collection was 0.004-0.06 mg/L, with a MIC50 of 0.016 mg/L and a MIC90 of 0.03 mg/L. The correlation between moenomycin and ceftriaxone susceptibility levels was poor (R = 0.13), while the fractional inhibitory concentration index (FICI) resulted in indifference for all tested strains. Therefore, development of cross-resistance between moenomycin and ceftriaxone is unlikely for N. gonorrhoeae. Determination of the moenomycin mode of activity against N. gonorrhoeae by time-kill assays showed that moenomycin is bactericidal, with over 104-fold inactivation observed after 4 h exposure. Finally, an intramuscular moenomycin dose of 10 mg/kg given on 2 consecutive days was able to clear a gonococcal infection in a mouse vaginal tract infection model within 1-3 days after the second dose, which was significantly faster than for mice treated with the vehicle control (P < 0.0001).

CONCLUSIONS

Moenomycin displays potent in vitro and in vivo antimicrobial activity against N. gonorrhoeae, warranting further exploration as alternative therapy.

Pharmacodynamic Evaluation of Zoliflodacin Treatment of Neisseria gonorrhoeae Strains With Amino Acid Substitutions in the Zoliflodacin Target GyrB Using a Dynamic Hollow Fiber Infection Model

Novel antimicrobials for effective treatment of uncomplicated gonorrhea are essential, and the first-in-class, oral spiropyrimidinetrione DNA gyrase B inhibitor zoliflodacin appears promising. Using our newly developed Hollow Fiber Infection Model (HFIM), the pharmacodynamics of zoliflodacin was examined. A clinical zoliflodacin-susceptible N. gonorrhoeae strain, SE600/18 (harbouring a GyrB S467N amino acid substitution; MIC = 0.25 mg/L), and SE600/18-D429N (zoliflodacin-resistant mutant with a second GyrB substitution, D429N, selected in the HFIM experiments; zoliflodacin MIC = 2 mg/L), were examined. Dose-range experiments, simulating zoliflodacin single oral dose regimens of 0.5, 1, 2, 3, and 4 g, were performed for SE600/18. For SE600/18-D429N, dose-range experiments, simulating zoliflodacin single oral 2, 3, 4, and 6 g doses, and zoliflodacin oral dose-fractionation experiments with 4, 6, and 8 g administered as q12 h were performed. Both strains grew well in the untreated HFIM growth control arms and mostly maintained growth at 10¹⁰–10¹¹ CFU/ml for 7 days. Zoliflodacin 3 and 4 g single dose oral regimens successfully eradicated SE600/18 and no growth was recovered during the 7-days experiments. However, the single oral 0.5, 1, and 2 g doses failed to eradicate SE600/18, and zoliflodacin-resistant populations with a GyrB D429N substitution were selected with all these doses. The zoliflodacin-resistant SE600/18-D429N mutant was not eradicated with any examined treatment regimen. However, this in vitro-selected zoliflodacin-resistant mutant was substantially less fit compared to the zoliflodacin-susceptible SE600/18 parent strain. In conclusion, the rare clinical gonococcal strains with GyrB S467N substitution are predisposed to develop zoliflodacin resistance and may require treatment with zoliflodacin ≥3 g. Future development may need to consider the inclusion of diagnostics directed at identifying strains resistant or predisposed to resistance development at a population level and to strengthen surveillance (phenotypically and genetically), and possibly also at the patient level to guide treatment.

First National Genomic Epidemiological Study of Neisseria gonorrhoeae Strains Spreading Across Sweden in 2016

The increasing transmission and antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a global health concern with worrying trends of decreasing susceptibility to also the last-line extended-spectrum cephalosporin (ESC) ceftriaxone. A dramatic increase of reported gonorrhea cases has been observed in Sweden from 2016 and onward. The aim of the present study was to comprehensively investigate the genomic epidemiology of all cultured N. gonorrhoeae isolates in Sweden during 2016, in conjunction with phenotypic AMR and clinical and epidemiological data of patients. In total, 1279 isolates were examined. Etest and whole-genome sequencing (WGS) were performed, and epidemiological data obtained from the Public Health Agency of Sweden. Overall, 51.1%, 1.7%, and 1.3% resistance to ciprofloxacin, cefixime, and azithromycin, respectively, was found. No isolates were resistant to ceftriaxone, however, 9.3% of isolates showed a decreased susceptibility to ceftriaxone and 10.5% to cefixime. In total, 44 penA alleles were found of which six were mosaic (n = 92). Using the typing schemes of MLST, NG-MAST, and NG-STAR; 133, 422, and 280 sequence types, respectively, and 93 NG-STAR clonal complexes were found. The phylogenomic analysis revealed two main lineages (A and B) with lineage A divided into two main sublineages (A1 and A2). Resistance and decreased susceptibility to ESCs and azithromycin and associated AMR determinants, such as mosaic penA and mosaic mtrD, were predominantly found in sublineage A2. Resistance to cefixime and azithromycin was more prevalent among heterosexuals and MSM, respectively, and both were predominantly spread through domestic transmission. Continuous surveillance of the spread and evolution of N. gonorrhoeae, including phenotypic AMR testing and WGS, is essential for enhanced knowledge regarding the dynamic evolution of N. gonorrhoeae and gonorrhea epidemiology.

Antimicrobial resistance prediction in Neisseria gonorrhoeae: Current status and future prospects

INTRODUCTION

Several nucleic acid amplification tests (NAATs), mostly real-time PCRs, to detect antimicrobial resistance (AMR) determinants and predict AMR in Neisseria gonorrhoeae are promising, and some may be ready to apply at the point-of-care (POC), but important limitations remain with most NAATs. Next-generation sequencing (NGS) can overcome many of these limitations.Areas covered: Recent advances, with main focus on publications since 2017, in the development and use of NAATs and NGS to predict gonococcal AMR for surveillance and clinical use, and pros and cons of these tests as well as future perspectives for appropriate use of molecular AMR prediction for N. gonorrhoeae.Expert Commentary: NAATs and/or NGS for AMR prediction should supplement culture-based AMR surveillance, which will remain because it detects also AMR due to unknown AMR determinants, and translation into POC tests is imperative for the end-goal of individualized treatment, sparing ceftriaxone±azithromycin. Several challenges for direct testing of clinical, especially pharyngeal, specimens and for accurate prediction of cephalosporins and azithromycin resistance, especially using NAATs, remain. The choice of AMR prediction assay needs to carefully consider the intended use of the assay; limitations intrinsic to the AMR prediction technology, algorithms and specific to chosen methodology; specimen types analyzed; and cost-effectiveness.

Genomic Analysis of the Predominant Strains and Antimicrobial Resistance Determinants Within 1479 Neisseria gonorrhoeae Isolates From the US Gonococcal Isolate Surveillance Project in 2018

BACKGROUND

The prevalence of Neisseria gonorrhoeae (GC) isolates with elevated minimum inhibitory concentrations to various antibiotics continues to rise in the United States and globally. Genomic analysis provides a powerful tool for surveillance of circulating strains, antimicrobial resistance determinants, and understanding of transmission through a population.

METHODS

Neisseria gonorrhoeae isolates collected from the US Gonococcal Isolate Surveillance Project in 2018 (n = 1479) were sequenced and characterized. Whole-genome sequencing was used to identify sequence types, antimicrobial resistance profiles, and phylogenetic relationships across demographic and geographic populations.

RESULTS

Genetic characterization identified that (1) 80% of the GC isolates were represented in 33 multilocus sequence types, (2) isolates clustered in 23 major phylogenetic clusters with select phenotypic and demographic prevalence, and (3) common antimicrobial resistance determinants associated with low-level or high-level decreased susceptibility or resistance to relevant antibiotics.

CONCLUSIONS

Characterization of this 2018 Gonococcal Isolate Surveillance Project genomic data set, which is the largest US whole-genome sequence data set to date, sets the basis for future prospective studies, and establishes a genomic baseline of GC populations for local and national monitoring.

Molecular characterization of Neisseria gonorrhoeae isolates collected through a national surveillance programme in Japan, 2013: evidence of the emergence of a ceftriaxone-resistant strain from a ceftriaxone-susceptible lineage

OBJECTIVES

To investigate the spread of ceftriaxone-resistant Neisseria gonorrhoeae lineages similar to strains H041 (2009) and FC428 (2015), we characterized 55 strains collected in 2013 from hospitals across Japan.

METHODS

Susceptibility testing and whole-genome sequencing.

RESULTS

Susceptibility rates were 58% for cefixime and 98% for ceftriaxone. The 55 strains were whole-genome sequenced and classified into nine MLST-STs. MLST-ST1901 was the most prevalent (n = 19) followed by MLST-ST7363 (n = 12) and MLST-ST7359 (n = 11). The most prevalent penA [encoding penicillin binding protein 2 (PBP2)] mosaic types, based on the N. gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR) scheme, were 10.001 (n = 20) followed by 34.001 (n = 13). The H041 and FC428 strains were not detected; however, a single ceftriaxone-resistant strain (TUM15748) with a MIC of 0.5 mg/L ceftriaxone was identified. The TUM15748 strain belonged to MLST-ST7359 and N. gonorrhoeae multiantigen sequence typing-ST6771, and had a novel PBP2 (PBP2TUM15748, penA type 169.001). The amino acid sequence of PBP2TUM15748 showed partial similarity to that of PBP2 from N. gonorrhoeae GU140106 and commensal Neisseria perflava and Neisseria cinerea. Natural transformation and recombination experiments using full-length TUM15748 penA showed that the ceftriaxone MICs of transformants increased 16-fold or more compared with the parental ceftriaxone-susceptible recipient strain (NG9807, belonging to MLST-ST7363). No ceftriaxone-resistant MLST-ST7359 strains have previously been reported.

CONCLUSIONS

We showed here that a ceftriaxone-susceptible lineage acquired a mutant PBP2 mosaic type, integrating partial PBP2 sequences from commensal Neisseria species, resulting in the emergence of ceftriaxone-resistant strains.

Phylogenomic analysis reveals persistence of gonococcal strains with reduced-susceptibility to extended-spectrum cephalosporins and mosaic penA-34

The recent emergence of strains of Neisseria gonorrhoeae associated with treatment failures to ceftriaxone, the foundation of current treatment options, has raised concerns over a future of untreatable gonorrhea. Current global data on gonococcal strains suggest that several lineages, predominately characterized by mosaic penA alleles, are associated with elevated minimum inhibitory concentrations (MICs) to extended spectrum cephalosporins (ESCs). Here we report on whole genome sequences of 813 N. gonorrhoeae isolates collected through the Gonococcal Isolate Surveillance Project in the United States. Phylogenomic analysis revealed that one persisting lineage (Clade A, multi-locus sequence type [MLST] ST1901) with mosaic penA-34 alleles, contained the majority of isolates with elevated MICs to ESCs. We provide evidence that an ancestor to the globally circulating MLST ST1901 clones potentially emerged around the early to mid-20th century (1944, credibility intervals [CI]: 1935-1953), predating the introduction of cephalosporins, but coinciding with the use of penicillin. Such results indicate that drugs with novel mechanisms of action are needed as these strains continue to persist and disseminate globally.

Antibiotic Treatment Regimes as a Driver of the Global Population Dynamics of a Major Gonorrhea Lineage

The Neisseria gonorrhoeae multilocus sequence type (ST) 1901 is among the lineages most commonly associated with treatment failure. Here, we analyze a global collection of ST-1901 genomes to shed light on the emergence and spread of alleles associated with reduced susceptibility to extended-spectrum cephalosporins (ESCs). The genetic diversity of ST-1901 falls into a minor and a major clade, both of which were inferred to have originated in East Asia. The dispersal of the major clade from Asia happened in two separate waves expanding from ∼1987 and 1996, respectively. Both waves first reached North America, and from there spread to Europe and Oceania, with multiple secondary reintroductions to Asia. The ancestor of the second wave acquired the penA 34.001 allele, which significantly reduces susceptibility to ESCs. Our results suggest that the acquisition of this allele granted the second wave a fitness advantage at a time when ESCs became the key drug class used to treat gonorrhea. Following its establishment globally, the lineage has served as a reservoir for the repeated emergence of clones fully resistant to the ESC ceftriaxone, an essential drug for effective treatment of gonorrhea. We infer that the effective population sizes of both clades went into decline as treatment schemes shifted from fluoroquinolones via ESC monotherapy to dual therapy with ceftriaxone and azithromycin in Europe and the United States. Despite the inferred recent population size decline, the short evolutionary path from the penA 34.001 allele to alleles providing full ceftriaxone resistance is a cause of concern.

Emergence and evolution of antimicrobial resistance genes and mutations in Neisseria gonorrhoeae

BACKGROUND

Antimicrobial resistance in Neisseria gonorrhoeae is a global health concern. Strains from two internationally circulating sequence types, ST-7363 and ST-1901, have acquired resistance to third-generation cephalosporins, mainly due to mosaic penA alleles. These two STs were first detected in Japan; however, the timeline, mechanism, and process of emergence and spread of these mosaic penA alleles to other countries remain unknown.

METHODS

We studied the evolution of penA alleles by obtaining the complete genomes from three Japanese ST-1901 clinical isolates harboring mosaic penA allele 34 (penA-34) dating from 2005 and generating a phylogenetic representation of 1075 strains sampled from 35 countries. We also sequenced the genomes of 103 Japanese ST-7363 N. gonorrhoeae isolates from 1996 to 2005 and reconstructed a phylogeny including 88 previously sequenced genomes.

RESULTS

Based on an estimate of the time-of-emergence of ST-1901 (harboring mosaic penA-34) and ST-7363 (harboring mosaic penA-10), and > 300 additional genome sequences of Japanese strains representing multiple STs isolated in 1996-2015, we suggest that penA-34 in ST-1901 was generated from penA-10 via recombination with another Neisseria species, followed by recombination with a gonococcal strain harboring wildtype penA-1. Following the acquisition of penA-10 in ST-7363, a dominant sub-lineage rapidly acquired fluoroquinolone resistance mutations at GyrA 95 and ParC 87-88, by independent mutations rather than horizontal gene transfer. Data in the literature suggest that the emergence of these resistance determinants may reflect selection from the standard treatment regimens in Japan at that time.

CONCLUSIONS

Our findings highlight how antibiotic use and recombination across and within Neisseria species intersect in driving the emergence and spread of drug-resistant gonorrhea.

Neisseria gonorrhoeae Antimicrobial Resistance: Past to Present to Future

Neisseria gonorrhoeae (gonococcus) is a Gram-negative bacterium that causes gonorrhoea-a sexually transmitted disease. This gonococcus has progressively developed resistance to most of the available antimicrobials. Only a few countries around the world have been able to run extensive surveillance programmes on gonococcal infection and antimicrobial resistance, raising a global concern. Thus, this review focuses on the mechanisms of resistance to recommended antimicrobials in the past and present time. The approaches by the scientific community in the development of novel technologies such as whole-genome sequencing to predict antimicrobial resistance, track gonococcal transmission, as well as, introduce new therapeutics like Solithromycin, Zoliflodacin, and Gepotidacin were also discussed.

Population-Level Antimicrobial Consumption Is Associated With Decreased Antimicrobial Susceptibility in Neisseria gonorrhoeae in 24 European Countries: An Ecological Analysis

OBJECTIVES

There are substantial variations between different populations in the susceptibility of Neisseria gonorrhoeae to antimicrobials, and the reasons for this are largely unexplored. We aimed to assess whether the population-level consumption of antimicrobials is a contributory factor.

METHODS

Using antimicrobial susceptibility data from 24 countries in the European Gonococcal Antimicrobial Surveillance Programme and antimicrobial consumption data from the IQVIA MIDAS database, we built mixed-effects linear/logistic regression models with country-level cephalosporin, fluoroquinolone, and macrolide consumption (standard doses/1000 population/year) as the explanatory variables (from 2009 to 2015) and 1-year-lagged ceftriaxone, cefixime, azithromycin, and ciprofloxacin geometric mean minimum inhibitory concentrations (MICs) as the outcome variables (from 2010 to 2016).

RESULTS

Positive correlations were found between the consumption of cephalosporins and the geometric mean MICs of ceftriaxone and cefixime (P < .05 for both comparisons). Fluoroquinolone consumption was positively associated with the prevalence of resistance to ciprofloxacin (P < .05).

CONCLUSIONS

Differences in the population-level consumption of particular antimicrobials may contribute to variations in the level of antimicrobial resistance in N. gonorrhoeae in different settings. Further interventions to reduce misuse and overuse of antimicrobials in high-consumption populations and core groups are required.

Impact of the gonococcal FC428 penA allele 60.001 on ceftriaxone resistance and biological fitness

Global dissemination of the Neisseria gonorrhoeae ceftriaxone-resistant FC428 clone jeopardizes the currently recommended ceftriaxone-based first-line therapies. Ceftriaxone resistance in the FC428 clone has been associated with the presence of its mosaic penA allele 60.001. Here we investigated the contribution penA allele 60.001 to ceftriaxone resistance and its impact on biological fitness. Gonococcal isolates expressing penA allele 60.001 and mosaic penA allele 10.001, which is widespread in the Asia-Pacific region and associated with reduced susceptibility to ceftriaxone and cefixime, were genetic engineered to exchange their penA alleles. Subsequent antimicrobial susceptibility analyses showed that mutants containing penA 60.001 displayed 8- to 16-fold higher ceftriaxone and cefixime minimal inhibitory concentrations (MICs) compared with otherwise isogenic mutants containing penA 10.001. Further analysis of biological fitness showed that in vitro liquid growth of single strains and in the competition was identical between the isogenic penA allele exchange mutants. However, in the presence of high concentrations of palmitic acid or lithocholic acid, the penA 60.001-containing mutants grew better than the isogenic penA 10.001-containing mutants when grown as single strains. In contrast, the penA 10.001 mutants outcompeted the penA 60.001 mutants when grown in competition at slightly lower palmitic acid or lithocholic acid concentrations. Finally, the penA 60.001 mutants were outcompeted by their penA 10.001 counterparts for in vivo colonization and survival in a mouse vaginal tract infection model. In conclusion, penA allele 60.001 is essential for ceftriaxone resistance of the FC428 clone, while its impact on biological fitness is dependent on the specific growth conditions.

Gonorrhoea treatment combined with population-level general cephalosporin and quinolone consumption may select for Neisseria gonorrhoeae antimicrobial resistance at the levels of NG-MAST genogroup: An ecological study in Europe

OBJECTIVES

The prevalence of Neisseria gonorrhoeae NG-MAST genogroup G1407, associated with decreased susceptibility to extended-spectrum cephalosporins and fluoroquinolone resistance, has declined in Europe and it switched from circulating predominantly in men who have sex with men (MSM) in 2009-2010 to heterosexuals in 2013. We hypothesise that changes to gonorrhoea treatment guidelines combined with differences in country-level consumption of cephalosporins and quinolones contributed to this shift.

METHODS

Linear regression was used to evaluate the association between changes in prevalence of G1407 between 2009-2010 and 2013 and country-level consumption of quinolones and cephalosporins in 2011/12 in 20 European countries.

RESULTS

Whilst the prevalence of G1407 declined between 2009-2010 and 2013 in the EU/EEA, its absolute prevalence increased by 10% or more in three countries. The national prevalence of G1407 in 2013 was positively associated with population-level general cephalosporin and quinolone consumption in the preceding 2 years. The association between the prevalence of G1407 and proportion of the national sample derived from MSM was non-significant in 2009-2010 and was negative in 2013.

CONCLUSIONS

Our results are broadly compatible with the hypothesis that changes in gonorrhoea therapy to the more efficacious ceftriaxone (plus azithromycin) from 2010 to 2011 onwards resulted in a reduced prevalence of the resistance-associated G1407 overall but in MSM in particular. High population-level consumption of quinolones and cephalosporins in certain countries then contributed to the selection of G1407 predominantly in heterosexuals in these countries.

Molecular Typing of Neisseria gonorrhoeae Clinical Isolates in Russia, 2018-2019: A Link Between penA Alleles and NG-MAST Types

This work aimed to study penA gene polymorphisms in clinical isolates of Neisseria gonorrhoeae collected in Russia in 2018-2019 and the contribution of the penA allele type to susceptibility to β-lactam antibiotics. A total of 182 isolates were analyzed. penA allele types were determined by sequencing, and the minimum inhibitory concentrations (MICs) of benzylpenicillin and ceftriaxone were measured. The influence of genetic factors on MICs was evaluated by regression analysis. All isolates were susceptible to ceftriaxone, and 40.1% of isolates were susceptible to penicillin. Eleven penA allele types were identified. The mosaic type XXXIV penA allele and the Gly120Lys substitution in PorB made the greatest contributions to increasing the ceftriaxone MIC; the presence of the bla_TEM plasmid, Gly120Asp, Ala121Gly/Asn substitutions in PorB, and the adenine deletion in the promoter region of the mtrR gene caused an increase in the penicillin MIC. Among 61 NG-MAST types identified, the most frequent were types 228, 807, 9486, 1993, and 6226. A link between penA alleles and Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST) types was established. Resistance to two groups of β-lactam antibiotics was associated with non-identical changes in penA alleles. To prevent the emergence of ceftriaxone resistance in Russia, NG-MAST genotyping must be supplemented with penA allele analysis.

Adaptation to the cervical environment is associated with increased antibiotic susceptibility in Neisseria gonorrhoeae

Neisseria gonorrhoeae is an urgent public health threat due to rapidly increasing incidence and antibiotic resistance. In contrast with the trend of increasing resistance, clinical isolates that have reverted to susceptibility regularly appear, prompting questions about which pressures compete with antibiotics to shape gonococcal evolution. Here, we used genome-wide association to identify loss-of-function (LOF) mutations in the efflux pump mtrCDE operon as a mechanism of increased antibiotic susceptibility and demonstrate that these mutations are overrepresented in cervical relative to urethral isolates. This enrichment holds true for LOF mutations in another efflux pump, farAB, and in urogenitally-adapted versus typical N. meningitidis, providing evidence for a model in which expression of these pumps in the female urogenital tract incurs a fitness cost for pathogenic Neisseria. Overall, our findings highlight the impact of integrating microbial population genomics with host metadata and demonstrate how host environmental pressures can lead to increased antibiotic susceptibility.

Genome-based epidemiology and antimicrobial resistance determinants of Neisseria gonorrhoeae isolates with decreased susceptibility and resistance to extended-spectrum cephalosporins in Argentina in 2011-16

OBJECTIVES

Our aim was to describe the molecular epidemiology and antimicrobial resistance determinants of isolates of Neisseria gonorrhoeae with decreased susceptibility and resistance to extended-spectrum cephalosporins (ESCs) in Argentina in 2011-16.

METHODS

Gonococcal isolates (n=158) with decreased susceptibility and resistance to ESCs collected in 2011-16 across Argentina were subjected to WGS and antimicrobial susceptibility testing for six antimicrobials.

RESULTS

In total, 50% of the isolates were resistant to cefixime, 1.9% were resistant to ceftriaxone, 37.3% were resistant to azithromycin and 63.9% of the isolates showed an MDR phenotype. Resistance and decreased susceptibility to ESCs was mainly associated with isolates possessing the mosaic penA-34.001, in combination with an mtrR promoter A deletion, and PorB1b amino acid substitutions G120K/A121N. Phylogenetic analysis revealed two main clades of circulating strains, which were associated with the N. gonorrhoeae multiantigen sequence typing (NG-MAST) ST1407 and closely related STs, and characterized by a high prevalence rate, wide geographical distribution and temporal persistence.

CONCLUSIONS

N. gonorrhoeae isolates with decreased susceptibility and resistance to ESCs in Argentina have emerged and rapidly spread mainly due to two clonal expansions after importation of one or two strains, which are associated with the international MDR NG-MAST ST1407 clone. The identification of the geographical dissemination and characteristics of these predominant clones may help to focus action plans and public health policies to control the spread of ESC resistance in Argentina. Dual antimicrobial therapy (ceftriaxone plus azithromycin) for gonorrhoea needs to be considered in Argentina.

A case of gonococcal meningitis caused by Neisseria gonorrhoeae MLST ST7363 in a healthy young adult

A 37-year-old healthy man was admitted with fever, skin rash, migratory arthralgia, and headache without preceding urogenital symptoms. Sexual contact history and positive CSF culture for Neisseria gonorrhoeae using BacT/Alert blood culture bottles were diagnostic for gonococcal meningitis. Multilocus sequence typing of this isolate showed sequence type (ST) 7363, the most predominant ST among ceftriaxone-resistant strains. The isolate from this case remained susceptible to ceftriaxone although it was resistant to penicillin, tetracycline, and ciprofloxacin. With the high selective pressure of ceftriaxone for treatment of plasmid-mediated β-lactamase producing N. gonorrhoeae, resistance to ceftriaxone and molecular characteristics should be monitored.

Comparative phylogenetic analysis of Neisseria gonorrhoeae clinical isolates in Russia, European Union, and Japan

Surveillance of multidrug-resistant infections is a priority task for contemporary epidemiology. The aim of this study was to genotype modern clinical isolates of N. gonorrhoeae using the NG-MAST technique (Neisseria gonorrhoeae multi-antigen sequence typing) and to compare the phylogeny of the gonococcal pathogens coming from Russia, European Union and Japan. We studied a total of 822 isolates collected in Russia from 2013 through 2018. We also used NG-MAST data from the following databases: PathogenWatch (European Union, 1,071 isolates) and PubMLST (Japan, 206 isolates). Russian isolates represented 301 different NG-MAST types. The most common were types 807, 228, 1993, 5714, and 9476 (8.3%, 3.3%, 3.2%, 3.2%, and 2.7%, respectively). There were only 3 isolates (0.4%) from Russia that represented the epidemiologically significant sequence type 1407 prevailing in many countries and characterized by multiple determinants of antimicrobial resistance. A phylogenetic tree for the NG-MAST types found in Russia and European countries was constructed. The cluster analysis of the proportion of isolates belonging to unique sequence types and the country population size allowed us to identify 2 clusters (significance level — 0.01): the first cluster included Russia and Japan, the second, European countries. A distribution pattern was identified for unique sequence types: the greater is the population size, the higher is their proportion. The phylogenetic analysis demonstrated a genetic distance between the most common Russian, European and Japanese sequence types, suggesting that the Russian population of N. gonorrhoeae has been evolving relatively locally.

Genetic diversity of Neisseria gonorrhoeae multi-antigen sequence types in Russia and Europe

OBJECTIVES

The goal of this work was to assess the genetic diversity of Neisseria gonorrhoeae isolates in Russia and Europe and to compare the distribution of the N. gonorrhoeae multi-antigen sequencing types (NG-MAST) of Russian isolates with that of isolates from European countries.

METHODS

NG-MAST typing was performed for 804 N. gonorrhoeae isolates collected in Russia in 2013-2018. For isolates from European countries, data from the https://pathogen.watch/collection/eurogasp2013 database were used.

RESULTS

Among the isolates from Russia, 296 NG-MAST types were found. A maximum likelihood phylogenetic tree was constructed. Phylogenetic analysis revealed seven major genogroups uniting the most frequent Russian sequence types: G807, G1993, G9476, G14942, G1152, G9486, and G12531.

CONCLUSIONS

The NG-MAST type distribution in Russia differed from that in European countries. Most of the Russian isolates had sequence types that were not found in Europe. Only 33% of the Russian isolates belonged to genogroups established for European countries, and the widespread European genogroup G1407 was represented by only nine isolates. Analysis of the Russian isolates belonging to phylogenetically close European genogroups indicated similarities in drug resistance, although no epidemically dangerous drug-resistant clones were found among the Russian isolates.

Increasing prevalence of Neisseria gonorrhoeae with decreased susceptibility to ceftriaxone and resistance to azithromycin in Hangzhou, China (2015-17)

Objectives

Development of resistance in Neisseria gonorrhoeae to ceftriaxone monotherapy or ceftriaxone plus azithromycin dual therapy is a global public health concern. The aim of this study was to analyse the trend in antimicrobial resistance in Hangzhou, China, over the period 2015-17.

Methods

In total, 379 clinical isolates were collected from seven hospitals and antimicrobial susceptibility was determined using the agar dilution method. Isolates showing resistance to ceftriaxone, azithromycin or cefixime were analysed for the presence of resistance determinants. STs were determined with the N. gonorrhoeae multiantigen sequence typing (NG-MAST) method and phylogenetic analysis and strain clustering was determined using porB and tbpB sequences.

Results

Ceftriaxone resistance, decreased susceptibility to ceftriaxone and azithromycin resistance were observed in 3%, 17% and 21% of the isolates, respectively. This resulted in 5% of the isolates showing both decreased susceptibility to ceftriaxone and azithromycin resistance. Importantly, resistance levels to ceftriaxone and azithromycin increased over the study period, resulting in 5% ceftriaxone resistance, 27% decreased susceptibility to ceftriaxone and 35% azithromycin resistance in 2017 and 11% of the isolates showing both decreased susceptibility to ceftriaxone and azithromycin resistance. Phylogenetic and cluster analysis showed the emergence and expansion in 2017 of a clonally related cluster containing strains with high abundance of decreased susceptibility to ceftriaxone and/or cefixime, which was related to the presence of the mosaic penA allele X. Co-resistance to azithromycin was also observed in this cluster.

Conclusions

Our findings have major implications for the future reliability of ceftriaxone monotherapy and ceftriaxone plus azithromycin dual therapy in China.

Where have all the susceptible gonococci gone? A historical review of changes in MIC distribution over the past 75 years

BACKGROUND

Does the emergence of antimicrobial resistance in Neisseria gonorrhoeae include the erasure of highly susceptible strains or does it merely involve a stretching of the MIC distribution? If it was the former this would be important to know as it would increase the probability that the loss of susceptibility is irreversible.

METHODS

We conducted a historical analysis based on a literature review of changes of N. gonorrhoeae MIC distribution over the past 75 years for 3 antimicrobials (benzylpenicillin, ceftriaxone and azithromycin) in five countries (Denmark, Japan, South Africa, the United Kingdom and the United States).

RESULTS

Changes in MIC distribution were most marked for benzylpenicillin and showed evidence of a right shifting of MIC distribution that was associated with a reduction/elimination of susceptible strains in all countries. In the case of ceftriaxone and azithromycin, where only more recent data was available, right shifting was also found in all countries but the extent of right shifting varied and the evidence for the elimination of susceptible strains was more mixed.

CONCLUSIONS

The finding of right shifting of MIC distribution combined with reduction/elimination of susceptible strains is of concern since it suggests that this shifting may not be reversible. Since excess antimicrobial consumption is likely to be responsible for this right shifting, this insight provides additional impetus to promote antimicrobial stewardship.

A Loop-Mediated Isothermal Amplification Assay Targeting Neisseria gonorrhoeae penA-60.001

Ceftriaxone (CRO) is widely used as the first-line treatment for gonococcal infections. However, CRO-resistant Neisseria gonorrhoeae strains carrying mosaic penA-60.001 have emerged recently and disseminated worldwide. To meet the urgent need to detect these strains, we report here a loop-mediated isothermal amplification (LAMP) assay system that targets N. gonorrhoeaepenA-60.001. This assay system can differentiate N. gonorrhoeae strains carrying mosaic penA-60.001 from strains carrying other penA alleles.

Antimicrobial Resistance And Molecular Characteristics Among Neisseria gonorrhoeae Clinical Isolates In A Chinese Tertiary Hospital

Purpose

The resistance of N. gonorrhoeae to antimicrobial agents has been increasing year by year due to the overuse of antibiotics. The primary aims of the present study were to investigate the molecular characteristics of the clinical isolates of Neisseria gonorrhoeae and the resistance to azithromycin in a Chinese tertiary hospital.

Methods

From January 2014 to May 2017, a total of 55 clinical isolates of N. gonorrhoeae were collected. Genes associated with azithromycin resistance (AZM-R), including mutations in 23S rRNA alleles, the mtrR promoter and coding regions, and rplD and rplV were evaluated by PCR and DNA sequencing. All clinical isolates were subjected to N. gonorrhoeae multiantigen sequence typing (NG-MAST), while the AZM-R isolates were further characterized by multilocus sequence typing (MLST).

Results

The AZM-R rate in this study was 23.64% (13/55), and a single (A)-nucleotide deletion mutation in the mtrR promoter region, a G45D mutation in the mtrR coding region, a point mutation in rplD, and an A2047G mutation in 23S rRNA alleles were detected in 13, 4, 3 and 4 isolates, respectively; no mutations were found in rplV. There was no significant difference in the mtrR coding region mutation rate between the azithromycin-sensitive and AZM-R groups (P > 0.05); however, there was a significant difference in the mutation rate of the mtrR promoter region (P < 0.05). Among the 55 isolates studied, 43 distinct NG-MAST were determined, while the AZM-R isolates were allocated into 10 distinct MLST/NG-MAST combinations. All three isolates with high-level AZM-R belonged to the sequence types (STs) NG-MAST ST1866 and MLST ST10899.

Conclusion

N. gonorrhoeae clinical isolates from Wenzhou, eastern China, showed considerable genetic diversity. Measures should be implemented to monitor the spread of the NG-MAST ST1866 and MLST ST10899 N. gonorrhoeae clones, which exhibit high-level AZM-R in eastern China.

Antimicrobial resistance (AMR) and molecular characterization of Neisseria gonorrhoeae in Ghana, 2012-2015

Neisseria gonorrhoeae antimicrobial resistance (AMR) surveillance is essential for tracking the emergence and spread of AMR strains in local, national and international populations. This is crucial for developing or refining treatment guidelines. N. gonorrhoeae multiantigen sequence typing (NG-MAST) is beneficial for describing the molecular epidemiology of gonococci at national and international levels. Elucidation of AMR determinants to β-lactam drugs, is a means of monitoring the development of resistance. In Ghana, little is known about the current gonococcal AMR prevalence and no characterization of gonococcal isolates has been previously performed. In this study, gonococcal isolates (n = 44) collected from five health facilities in Ghana from 2012 to 2015, were examined using AMR testing, NG-MAST and sequencing of penA. High rates of resistance were identified to tetracycline (100%), benzylpenicillin (90.9%), and ciprofloxacin (81.8%). One isolate had a high cefixime MIC (0.75 μg/ml). Twenty-eight NG-MAST sequence types (STs) were identified, seventeen of which were novel. The isolate with the high cefixime MIC contained a mosaic penA-34 allele and belonged to NG-MAST ST1407, an internationally spreading multidrug-resistant clone that has accounted for most cefixime resistance in many countries. In conclusion, AMR testing, NG-MAST, and sequencing of the AMR determinant penA, revealed high rates of resistance to tetracycline, benzylpenicillin, and ciprofloxacin; as well as a highly diverse population of N. gonorrhoeae in Ghana. It is imperative to continue with enhanced AMR surveillance and to understand the molecular epidemiology of gonococcal strains circulating in Ghana and other African countries.

Using the genetic characteristics of Neisseria gonorrhoeae strains with decreased susceptibility to cefixime to develop a molecular assay to predict cefixime susceptibility

BACKGROUND

In the last two decades, gonococcal strains with decreased cefixime susceptibility and cases of clinical treatment failure have been reported worldwide. Gonococcal strains with a cefixime minimum inhibitory concentration (MIC) ≥0.12 µg mL-1 are significantly more likely to fail cefixime treatment than strains with an MIC <0.12 µg mL-1. Various researchers have described the molecular characteristics of gonococcal strains with reduced cefixime susceptibility, and many have proposed critical molecular alterations that contribute to this decreased susceptibility.

METHODS

A systematic review of all published articles in PubMed through 1 November 2018 was conducted that report findings on the molecular characteristics and potential mechanisms of resistance for gonococcal strains with decreased cefixime susceptibility. The findings were summarised and suggestions were made for the development of a molecular-based cefixime susceptibility assay.

RESULTS

The penicillin-binding protein 2 (PBP2) encoded by the penA gene is the primary target of cefixime antimicrobial activity. Decreased cefixime susceptibility is conferred by altered penA genes with mosaic substitute sequences from other Neisseria (N.) species (identifiable by alterations at amino acid position 375-377) or by non-mosaic penA genes with at least one of the critical amino acid substitutions at positions 501, 542 and 551. Based on this review of 415 international cefixime decreased susceptible N. gonorrhoeae isolates, the estimated sensitivity for an assay detecting the aforementioned amino acid alterations would be 99.5% (413/415).

CONCLUSIONS

Targeting mosaic penA and critical amino acid substitutions in non-mosaic penA are necessary and may be sufficient to produce a robust, universal molecular assay to predict cefixime susceptibility.

Emergence and Spread of Cephalosporin-Resistant Neisseria gonorrhoeae with Mosaic penA Alleles, South Korea, 2012-2017

In South Korea, surveillance of antimicrobial drug resistance in Neisseria gonorrhoeae is extremely limited. We describe the emergence and subsequent national spread of N. gonorrhoeae strains with mosaic penA alleles associated with decreased susceptibility and resistance to extended-spectrum cephalosporins. From 2012 through 2017, the proportion of mosaic penA alleles in gonococcal-positive nucleic acid amplification test (NAAT) specimens across South Korea increased from 1.1% to 23.9%. Gonococcal strains with mosaic penA alleles emerged in the international hubs of Seoul in Gyeonggi Province and Busan in South Gyeongsang Province and subsequently spread across South Korea. Most common was mosaic penA-10.001 (n = 572 isolates; 94.7%), which is associated with cefixime resistance. We also identified mosaic penA-34.001 and penA-60.001, both of which are associated with multidrug-resistant gonococcal strains and spread of cefixime and ceftriaxone resistance. Implementation of molecular resistance prediction from N. gonorrhoeae–positive nucleic acid amplification test specimens is imperative in South Korea and internationally.

Resistance of Neisseria gonorrhoeae isolates to beta-lactam antibiotics (benzylpenicillin and ceftriaxone) in Russia, 2015-2017

The goal of this work was to study the phenotypic susceptibility and resistance determinants of N. gonorrhoeae isolates to beta-lactam antimicrobials (benzylpenicillin and ceftriaxone). A total of 522 clinical isolates collected in Russia in 2015–2017 were analysed for susceptibility using the agar dilution method. DNA loci involved in antimicrobial resistance were identified using DNA microarray analysis and sequencing. Resistance to benzylpenicillin remained high, with 7.7% of isolates resistant (MIC_pen > 1 mg/L) and 47.5% of isolates showing intermediate susceptibility (MIC_pen = 0.12–1 mg/L). The most frequent resistance determinant (72.4% isolates) was the Asp345 insertion in penA, both as a single mutation and in combination with other mutations, particularly with the substitution Leu421Pro in ponA (39.0%). Mutations affecting the influx and efflux of drugs were also found, including amino acid substitutions in PorB (26.8% isolates) and delA in the promoter region of mtrR (22.8%). The accumulation of mutations in chromosomal genes (penA, pon, porA, and mtrR) led to a stepwise increase in MIC_pen to values characteristic of intermediate resistance. The presence of bla_TEM plasmids was found in 25 isolates (4.8%), resulting in a strong increase in resistance to penicillin (MIC_pen > 16 mg/L) compared with the chromosomal mutations; 23 plasmids were of the African type with TEM-1 beta-lactamase, and two plasmids were of the Toronto/Rio type with TEM-135 beta-lactamase. Only three isolates were found with reduced susceptibility to ceftriaxone, with MIC_cef = 0.12–0.25 mg/L. Sequencing of penA did not reveal mutations associated with resistance to third-generation cephalosporins, and the gene structure was non-mosaic. The majority of isolates (21 of 25) carrying the bla_TEM plasmid also contained the conjugative plasmid with tetM (resistance to tetracyclines), consistent with previously reported data that the presence of the conjugative plasmid facilitates the transfer of other plasmids associated with antimicrobial resistance.

Cephalosporin-Resistant Neisseria gonorrhoeae Clone, China

Cephalosporin-resistant Neisseria gonorrhoeae is a major public health concern. N. gonorrhoeae of multiantigen sequence type G1407 and multilocus sequence type 1901 is an internationally spreading cephalosporin-resistant clone. We detected 4 cases of infection with this clone in China and analyzed resistance determinants by using N. gonorrhoeae sequence typing for antimicrobial resistance.

Using genomics to understand antimicrobial resistance and transmission in Neisseria gonorrhoeae

Gonorrhoea infections are on the increase and strains that are resistant to all antimicrobials used to treat the disease have been found worldwide. These observations encouraged the World Health Organization to include Neisseria gonorrhoeae on their list of high-priority organisms in need of new treatments. Fortunately, concurrent resistance to both antimicrobials used in dual therapy is still rare. The fight against antimicrobial resistance (AMR) must begin from an understanding of how it evolves and spreads in sexual networks. Genome-based analyses have allowed the study of the gonococcal population dynamics and transmission, giving a novel perspective on AMR gonorrhoea. Here, we will review past, present and future treatment options for gonorrhoea and explain how genomics is helping to increase our understanding of the changing AMR and transmission landscape. This article contains data hosted by Microreact.

Evaluation of Susceptibilities to Carbapenems and Faropenem Against Cephalosporin-Resistant Neisseria gonorrhoeae Clinical Isolates with penA Mosaic Alleles

Neisseria gonorrhoeae is a principal pathogen for sexually transmitted infections, especially for male urethritis. Currently, the prevalence of multidrug resistance is increasing. Carbapenems are broad-spectrum antimicrobials that are widely used in the clinical setting, especially for multidrug-resistant Gram-negative bacteria. However, susceptibility to carbapenems has not been well evaluated for cephalosporin-resistant N. gonorrhoeae isolates. In this study, we determined the susceptibility to a series of carbapenems (meropenem, imipenem, doripenem, and biapenem) and faropenem against cephalosporin-resistant (resistant to cefixime, but susceptible to ceftriaxone) and cephalosporin-susceptible N. gonorrhoeae clinical isolates. The gene mutations associated with β-lactam resistance were evaluated. All cephalosporin-resistant N. gonorrhoeae isolates possessed mosaic mutation alleles in penA (NG-STAR penA-10.001, 27.001, or 108.001). They exhibited a low minimum inhibitory concentration (MIC) (≤0.125 mg/L) for meropenem and markedly high MICs (0.5-2 mg/L) for other carbapenems and faropenem. The strongest association was observed between the mosaic alleles in penA and decreased susceptibility to carbapenems and faropenem compared with mutations in mtrR, porB, and ponA. These results suggest that meropenem may serve as an alternative therapeutic agent for cephalosporin-resistant N. gonorrhoeae with a mosaic allele in penA, whereas other carbapenems and faropenem may be ineffective.

Antibiotic resistance and NG-MAST sequence types of Neisseria gonorrhoeae isolates in Poland compared to the world

Gonorrhoea is one of the most common sexually transmitted infections and in 2012, the World Health Organization estimated about 78 million of new global urogenital cases among adults per year. The main concern during the latest decade has been the emergence and spread of multidrug-resistant strains of Neisseria gonorrhoeae. Resistance has emerged internationally to the extended-spectrum cephalosporins, ceftriaxone and cefixime, which are the last remaining options for empiric first-line monotherapy of gonorrhoea. In Poland, the levels of resistance to ciprofloxacin, benzylpenicillin and tetracycline are high, and the prevalence of azithromycin resistance has increased. However, no resistance to ceftriaxone has been identified. The currently spread multidrug-resistant strains frequently represent epidemic clones. The present paper reviews and describes the antimicrobial resistance and N. gonorrhoeae multiantigen sequence typing (NG-MAST) sequence types of N. gonorrhoeae strains spreading in Poland compared to the world.

Genomic surveillance of Neisseria gonorrhoeae to investigate the distribution and evolution of antimicrobial-resistance determinants and lineages

The first extensively drug resistant (XDR) Neisseria gonorrhoeae strain with high resistance to the extended-spectrum cephalosporin ceftriaxone was identified in 2009 in Japan, but no other strain with this antimicrobial-resistance profile has been reported since. However, surveillance to date has been based on phenotypic methods and sequence typing, not genome sequencing. Therefore, little is known about the local population structure at the genomic level, and how resistance determinants and lineages are distributed and evolve. We analysed the whole-genome sequence data and the antimicrobial-susceptibility testing results of 204 strains sampled in a region where the first XDR ceftriaxone-resistant N. gonorrhoeae was isolated, complemented with 67 additional genomes from other time frames and locations within Japan. Strains resistant to ceftriaxone were not found, but we discovered a sequence type (ST)7363 sub-lineage susceptible to ceftriaxone and cefixime in which the mosaic penA allele responsible for reduced susceptibility had reverted to a susceptible allele by recombination. Approximately 85 % of isolates showed resistance to fluoroquinolones (ciprofloxacin) explained by linked amino acid substitutions at positions 91 and 95 of GyrA with 99 % sensitivity and 100 % specificity. Approximately 10 % showed resistance to macrolides (azithromycin), for which genetic determinants are less clear. Furthermore, we revealed different evolutionary paths of the two major lineages: single acquisition of penA X in the ST7363-associated lineage, followed by multiple independent acquisitions of the penA X and XXXIV in the ST1901-associated lineage. Our study provides a detailed picture of the distribution of resistance determinants and disentangles the evolution of the two major lineages spreading worldwide.

Antimicrobial resistance and molecular epidemiology using whole-genome sequencing of Neisseria gonorrhoeae in Ireland, 2014-2016: focus on extended-spectrum cephalosporins and azithromycin

High-level resistance and treatment failures with ceftriaxone and azithromycin, the first-line agents for gonorrhoea treatment are reported and antimicrobial-resistant Neisseria gonorrhoeae is an urgent public health threat. Our aims were to determine antimicrobial resistance rates, resistance determinants and phylogeny of N. gonorrhoeae in Ireland, 2014-2016. Overall, 609 isolates from four University Hospitals were tested for susceptibility to extended-spectrum cephalosporins (ESCs) and azithromycin by the MIC Test Strips. Forty-three isolates were whole-genome sequenced based on elevated MICs. The resistance rate to ceftriaxone, cefixime, cefotaxime and azithromycin was 0, 1, 2.1 and 19%, respectively. Seven high-level azithromycin-resistant (HLAzi-R) isolates were identified, all susceptible to ceftriaxone. Mosaic penA alleles XXXIV, X and non-mosaic XIII, and G120K plus A121N/D/G (PorB1b), H105Y (MtrR) and A deletion (mtrR promoter) mutations, were associated with elevated ESC MICs. A2059G and C2611T mutations in 23S rRNA were associated with HLAzi-R and azithromycin MICs of 4-32 mg/L, respectively. The 43 whole-genome sequenced isolates belonged to 31 NG-MAST STs. All HLAzi-R isolates belonged to MLST ST1580 and some clonal clustering was observed; however, the isolates differed significantly from the published HLAzi-R isolates from the ongoing UK outbreak. There is good correlation between previously described genetic antimicrobial resistance determinants and phenotypic susceptibility categories for ESCs and azithromycin in N. gonorrhoeae. This work highlights the advantages and potential of whole-genome sequencing to be applied at scale in the surveillance of antibiotic resistant strains of N. gonorrhoeae, both locally and internationally.

Surveillance of Antibiotic Susceptibility Patterns of Neisseria gonorrhoeae from 2013 to 2015 in Guangxi Province, China

Neisseria gonorrhoeae is a sexually transmitted pathogen highly prevalent worldwide with an increasing trend of resistance to antimicrobial treatment. We conducted this study to trace the susceptibility of N. gonorrhoeae to penicillin (PC), spectinomycin (SPCM), ciprofloxacin (CPFX), azithromycin (AZM), cefixime (CFIX), and ceftriaxone (CTRX) in Guangxi province. In total, 303 N. gonorrhoeae isolates were obtained from patients infected with N. gonorrhoeae in 6 cities in Guangxi during 2013-2015, and the antibiotic susceptibility patterns were analyzed by an agar dilution assay. The results showed that N. gonorrhoeae was susceptible to treatment with cephalosporins, including CTRX (99.7% of isolates), CFIX (99%), SPCM (100%), and AZM (96.4%), and this is the first report of antibiotic susceptibility for AZM surveillance of N. gonorrhoeae in Guangxi. Penicillinase-producing N. gonorrhoeae (PPNG) isolates increased in prevalence from 37% in 2013 to 64% in 2015 (P = 0.068), and tetracycline-resistant N. gonorrhoeae (TRNG) prevalence increased from 23% in 2013 to 44% in 2015 (P = 0.071). High resistance of N. gonorrhoeae to PC was associated with infection in patients at ages 25 to 30 years (P ＜ 0.05), whereas PPNG positivity (P ＜ 0.01), and TRNG positivity were risk factors for CPFX resistance (P = 0.0407). Our study provides plausible evidence for therapeutic strategies and N. gonorrhoeae infection control and prevention in Guangxi, China.

Fitness cost and benefit of antimicrobial resistance in Neisseria gonorrhoeae: Multidisciplinary approaches are needed

In a Perspective on the research article by Didelot and colleagues, Magnus Unemo and Christian Althaus discuss the value of modelling studies to inform antimicrobial resistance management and the limitations of the current evidence base informing such models.

Recent advances in the development and use of molecular tests to predict antimicrobial resistance in Neisseria gonorrhoeae

INTRODUCTION

The number of genetic tests, mostly real-time PCRs, to detect antimicrobial resistance (AMR) determinants and predict AMR in Neisseria gonorrhoeae is increasing. Several of these assays are promising, but there are important shortcomings and few assays have been adequately validated and quality assured. Areas covered: Recent advances, focusing on publications since 2012, in the development and use of molecular tests to predict gonococcal AMR for surveillance and for clinical use, advantages and disadvantages of these tests and of molecular AMR prediction compared with phenotypic AMR testing, and future perspectives for effective use of molecular AMR tests for different purposes. Expert commentary: Several challenges for direct testing of clinical, especially extra-genital, specimens remain. The choice of molecular assay needs to consider the assay target, quality controls, sample types, limitations intrinsic to molecular technologies, and specific to the chosen methodology, and the intended use of the test. Improved molecular- and particularly genome-sequencing-based methods will supplement AMR testing for surveillance purposes, and translate into point-of-care tests that will lead to personalized treatments, while sparing the last available empiric treatment option (ceftriaxone). However, genetic AMR prediction will never completely replace phenotypic AMR testing, which detects also AMR due to unknown AMR determinants.

Genomic sequencing of Neisseria gonorrhoeae to respond to the urgent threat of antimicrobial-resistant gonorrhea

The development of resistance of Neisseria gonorrhoeae to available first-line antibiotics, including penicillins, tetracyclines, fluoroquinolones and cephalosporins, has led to the circulation of multidrug-resistant gonorrhea at a global scale. Advancements in high-throughput whole-genome sequencing (WGS) provide useful tools that can be used to enhance gonococcal detection, treatment and management capabilities, which will ultimately aid in the control of antimicrobial resistant gonorrhea worldwide. In this minireview, we discuss the application of WGS of N. gonorrhoeae to strain typing, phylogenomic, molecular surveillance and transmission studies. We also examine the application of WGS analyses to the public health sector as well as the potential usage of WGS-based transcriptomic and epigenetic methods to identify novel gonococcal resistance mechanisms.